A global navigation satellite system comprises, among other things, a so called constellation of multiple navigation satellites, which are orbiting the earth and which each transmit dedicated navigation signals also called ‘ranging signals’. Global navigation satellite systems can be: the NAVSTAR Global Positioning System (GPS), the Global'naya Navigatsionnaya Sputnikovaya Sistema (GLONASS) (which is actually translated into Global Navigation Satellite System but which is not to be confused with GNSS), Galileo or any future navigation satellite constellation.
Global navigation satellite signal reception functionality enables a device to receive, acquire and track the global navigation satellites' ranging signals. Global navigation satellite signal processing functionality further enables the act of determining geographic position (positioning), location (locating) and course of any person, vessel or object equipped with a navigation receiver. This functionality is also generally called the Position, Velocity and Time (PVT) solution. This solution is usually based on the ranging signals received from at least four global navigation satellites.
A ‘satellite based augmentation system’ (SBAS) uses a network of geo-stationary satellites and ground stations to enhance the performance of a Global Navigation Satellite System by providing differential correction signals to the navigation receiver users. Satellite based augmentation systems can be the Wide Area Augmentation System (WAAS), the European Geostationary Navigation Overlay System (EGNOS), the Multi-Functional Satellite Augmentation System (MSAS) or any other or future satellite based augmentation system. SBAS satellites usually transmit signals in the same format and on the same frequency as the Global Navigation Satellite System's ranging signals. Hence, devices capable of receiving navigation satellite signals are usually also capable of receiving signals from SBAS systems or any other navigation augmentation system using the same type of ranging signals.
A ‘pseudolite’ (contraction of the term ‘pseudo-satellite’) is a device that is not a satellite, but performs a function commonly in the domain of satellites. Pseudolites are most often transceivers that are used to create a local, ground-based satellite alternative in situations where the normal satellite signals are not available (e.g. because they are blocked, jammed, highly attenuated, not existing). Pseudolites can be used for providing a navigation satellite alternative for navigation signal users e.g. in underground parking lots or tunnels. They are also used for testing purposes, for example for emulating a not yet existing navigation satellite constellation. Devices capable of receiving navigation satellite signals are also capable of receiving signals from pseudolites and/or any other device designed to transmit or transceive navigation signals.
A user is enabled to pinpoint his/her geographic location anywhere in the world by means of a device equipped with a global navigation satellite signal reception and processing functionality (hereafter called ‘navigation receiver’). FIG. 1 shows a schematic diagram of a navigation receiver. It shows the elementary functional blocks of a navigation receiver (10): antenna (11), receiver radio frequency (RF) front end (13), navigation signal baseband (BB) processor (15) and a navigation processor (17) including the positioning, velocity and time (PVT) calculation software (18) and a receiver configuration & control block (19).
FIG. 2 shows how a navigation receiver (10) can be integrated in a communication device (1) comprising a device for mobile wireless communication (e.g. a mobile telephone) providing the user the combined ability of personal wireless communication and navigation by means of an application processor (50). The application processor among other things, transmits the information from the navigation receiver to the end user application, e.g. a map to be displayed on the screen of the navigation device. The wireless communication link can be based on standards such as GSM, WCDMA, UMTS, CDMA2000, EDGE, GPRS or any future communication scheme. FIG. 2 shows how a navigation receiver (10) and a communications transmitter/receiver (20) can co-exist. A means for interaction between the communication transceiver (20) and the navigation receiver (10) can be provided for assisted global satellite navigation.
Assisted global satellite navigation is an enhanced satellite navigation concept that uses a so called assistance data server and a communications network to aid the navigation operation of a navigation receiver by means of the interaction possibility between the communication receiver and navigation receiver. At start-up, i.e. when a navigation receiver is powered up, it takes a considerable amount of time for the receiver to receive, track and process all the satellite signals before being able to provide the application processor with acceptable position, velocity and time information. Navigation assistance functionality enables a device containing at least both a navigation receiver and a wireless communications receiver with interacting possibilities to perform a faster reception, acquisition, tracking and processing of the navigation satellite's signals at start-up based on assistance data (reference location, reference time, corrections and satellite information). The assistance data is transmitted from the assistance server via the communications network, handled by the device's communication receiver and transmitted to the navigation receiver. The interaction port (assistance data port) between the wireless communication and the navigation receiver is used in order to transfer the assistance data.
The assistance data can be employed by the navigation receiver at two different levels, as shown in FIG. 3: either at the level of the navigation signal baseband processor (15) for speeding up the acquisition and tracking or at the level of the level of the navigation processor (17) for increasing the speed of the position, velocity and time calculation. Both possibilities can be implemented together as well.
The design and manufacturing test of mobile communication devices nowadays can be automated to a great extent. State of the art test hardware for e.g. mobile phone manufacturing can be used at the end of the production line for pass/fail decisions. The test device establishes a test-call to the device under test and performs hardware verification, protocol, performance and conformance tests on the device under test during that test-call. It is obvious that, in particular for manufacturing test, a high level of automation and test time reduction is a priority.
When testing the navigation receiver functionality embedded in a communication device, which is enabled both for navigation and wireless mobile communication, several drawbacks are encountered. Firstly, a wired connection to the communication device would be required for testing the navigation functionality (i.e. for reading out test values etc. . . . ). This greatly increases the time needed for the test, which is unacceptable for e.g. production line testing. Secondly, hardware components need to be reconfigured in a test mode and furthermore one needs to wait for a full position fix.